The present invention pertains to a support material that can serve as mattress, cushion or padding an is made of small balloon shaped cells filled with a fluid. These cells are interconnected at their base in order to create a single volume of fluid which fills all the cells, the type of fluid being selected according to the application. The cell layout is designed to yield the lowest possible cell density (number of cells per unit of area of the support) while offering a supporting surface as uniform as possible and capable of closely conforming to the contour of the supported body once they are filled.
This support material can be used in the medical field, for mattresses and cushions designed to prevent bed sores or for protective padding, such as those present in dorsolumbar supports or to protect fragile equipment.
These types of support material are already known in terms of the ability of their bearing surface to conform to the supported body while presenting the same reaction regardless of the degree of compression of the support, due to the pressure equalization among the interconnected cells. This is described by JAY in U.S. Pat. No. 4,726,624, U.S. Pat. No. 5,018,790 and U.S. Pat. No. 5,369,829 relating to cushions, where a sheath made of several oversized sheets assembled in the same plane is filled with gel and placed on a shaped seat of smaller dimensions. This case sheaths contains longitudinal and transverse chambers which are interconnected in such a manner that when someone is sitting, the pressure is equalized among the various chambers. In position, the sheath can be perceived as an array of longitudinal and transverse cylindrical balloons which are elevated above the median plane of the seam of the sheath, the disadvantage being the presence of numerous folds which could constrict the blood circulation in the skin.
We know the bed described by HINSDALE in U.S. 945234, whose mattress is made of a staggered array of small spherical balloons, the top of these being the bearing surface characterized by the most uniform pressure over the entire supporting area. The balloons are inflated with air, circulation of which is possible, and they are all interconnected at their bottom via a network of tubes, thus creating a single air chamber where each balloon sees the same air pressure.
In WO 96/08185, Ouiger describes how a compensation chamber regulates the pressure within an air mattress. In EP 0651 959A1, Txc3x6dter describes a bellow type of cellular support. In EP 0651 162A2, Kawasaki describes a cellular support made of non-expansible square cells located on either side (top and bottom) of the seam plane, with cross-braces where the rows intersect. Iskra, in U.S. Pat. No. 5,487,197 describes a controlled support with non-expansible longitudinal inflatable cells. In WO 96/19997, Holdredge describes a support equipped with a turbine, which includes non-expansible inflatable bladders. Caldwell in WO 93/24089, Johnson in WO 94/19998 (U.S. Pat. No. 5,373,595) and Evans in WO 95/15706 describe controlled supports with elongated inflatable bladders. In EP 0566 507A1, Beaud describes a support consisting of inflatable elements made of two sheets, with an internal wall on the seam plane of the two sheets. In JP 07000257, Yamamoto Giichi describes a vibration absorbing cushion designed for vehicle drivers. In JP 04030814 and JP 04030813, Sagami Masaharu describes the behavior of a inflatable cell mattress. In JP 03039105, Hiochi Toshimichi describes the flow regulation (air or water) within a support. Supports which rely on regulation or dynamic assistance have one disadvantage which is their cost. Without objecting to a possible usage of assisted supports, the present invention provides a support which does not need any type assistance to operate, like some previously mentioned supports from HINSDALE, GRAEBE, BENGUIGUI or VIESTURS. In addition, some medical supports have a disadvantage in that they favor the xe2x80x9chammock effectxe2x80x9d which contributes to a shearing of the skin and hinders blood circulation. For instance, in the case of the Hinsdale product used to prevent bed sores, this undesirable effect can be avoided by removing the upper fabric layer or by replacing it with a highly extensible fabric such as jersey.
Patent GB 1341325 describes a mattress somewhat similar in principle, which is inflated with a turbine, also described by DOUGLAS in U.S. Pat. No. 4,279,044.
Patent JP 05081423, by Ichida Michiyasu describes a regulation system in a mattress consisting of truncated conical cells.
Such supports can be improved by using small balloons or conical cells described by GRAEBE in U.S. Pat. No. 3,605,145, which are interconnected via small ducts at the bottom of the cells, these ducts appearing automatically when the sheets are assembled together. GRAEBE then goes on to describe cells whose cross-section is in the shape of a star, in which the walls of the inflated balloons can expand beyond the position and volume they occupy when deflated. It is therefore possible to arrange these cells or balloons upright on their bottom in longitudinal or transverse rows while maintaining a uniform bearing surface upon inflation, which would not be the case with the balloons described by HINSDALE in U.S. 945234 if they were arranged in the same configuration. The GRAEBE invention pertaining to the cell expansion led in 1975 and 1977 to the U.S. Pat. Nos. 3,870,450 and 4,005,236, in which he details the mold required to manufacture a support and describes the resulting support identical in nature to the previous one in .S. Pat. No. 3,605,145, and characterized by the expansion and interconnection of the cells via bottom ducts created by the assembly of the two sheets, the upper sheet being shaped, the lower sheet being flat, such as he also describes in the U.S. design patent D35558. The deflated cells can be contained within a virtual sheath having a round, square, rectangular cross section and they can be uniform or not from top to bottom, with or without a foot (US. Pat. No. 3,605,145 and U.S. Pat. No. 3,870,450), as also indicate by EVANS in U.S. Pat. No. 4,864,671, the type of inflating fluid being irrelevant. The interconnecting system between cells filled with a liquid has also been described by VIESTURS in U.S. Pat. No. 4,422,194, for a cellular support presenting a square cross-section and resulting from the assembly of formed sheets located on either side of the seam plane. SEBAG and BENGUIGUI in U.S. Pat. No. 5,553,220 (EP 0721755A1) describe an alternate cellular design with four branches or ribs having parallel sides. The lateral concavities in the contiguous cells facing each other, they basically reproduce the description of the distribution grid in FR 270873.
In De-U-9410601, ROUSCHAL describes some cells but focuses mostly on a cell interconnecting network obtained by gluing the formed top sheet and the flat bottom sheet around the perimeter of the support only.
In U.S. Pat. No. 4,541,136, GRAEBE also described a simple cell shape having only four branches, such as half the deflated bladder of a pigskin football, the cross-section of which has the shape of a cross, the four branches of the star or cross of GRAEBE ending at the four corners of a square. In the previous art, the two side walls or faces of the ridges of the mandrel and therefore of the ridges of the cells also are relatively close and parallel: U.S. Pat. No. 4,005,236 (col 3, line 13-radially directed ribs) and U.S. Pat. No. 4,541,136 (claim 2: pair of closely spaced side walls). In U.S. Pat. No. 4,864,671, EVANS call these ribs xe2x80x9cridgesxe2x80x9d and the cell side walls xe2x80x9cfoldsxe2x80x9d where GRAEBE in U.S. Pat. No. 4,541,136 instead uses xe2x80x9cdepressed side wallsxe2x80x9d. Furthermore, in U.S. Pat. No. 4,005,603 and U.S. Pat. No. 5,052,068, Graebe gives a broad description of cells of various cross-sections, which does not detail the various rib shapes except in terms of their radial configuration in U.S. Pat. No. 4,005,236 and their two parallel side walls in U.S. Pat. No. 4,541,136 as previously indicated. As we shall see in the description of this invention, its distinction and advantage are also demonstrated by comparing the shapes of the ribs with two side walls from the previous art with the shape of the ribs in this invention. Not taking into account the supposedly different mechanical properties of the multi-branched or multi-ribbed cells previously described by GRAEBE, this simple shape makes it much easier to fabricate the male mandrels required to manufacture the cells. The mandrels can be cast between two dies, the seam between the dies lying in the cell sagittal axis. This two-die casting process can be applied to any product except aluminum. Each die, preferably a metal die, cast a full branch or rib of the mandrel and a side wall of two contiguous branches, as in the cell described in U.S. Pat. No. 5,553,220, in which case the xe2x80x9cseam planexe2x80x9d of the two dies is not a plane but rather takes the form of a xe2x80x9cZxe2x80x9d, thus avoiding the sand casting of mandrels, often made in aluminum, which is required to produce supports such as cushions. This four branched star shape is the only one allowing a one-piece dipping mandrel manufactured using two rigid dies. Indeed, to create a three branch cell, three dies are needed, and for a five branch cell, five dies. The sand casting of aluminum mandrels is inexpensive, but the resulting surface is rough. Some lost wax casting processes are ideal but expensive. Machining the cell mandrels is a very expensive proposition. The casting of a complete cell mandrel (top, body base) can be done in one piece using flexible elastomer molds: it is also possible to extrude the body and assembly it to the top and the base, the interconnection of the cells being achieved using the description which is in the public domain. Based on the same principle of pressure equalization, GRAEBE has filed U.S. Pat. No. 4,698,864, the application WO 94/10881, U.S. Pat. No. 5,163,196 and U.S. Pat. No. 4,502,855. In U.S. Pat. No. 5,369,828, and in U.S. Pat. Nos.5,551,107 and 5,561,875 as well, GRAEBE describes non-expansible pyramid shaped cells; but also in WO 93/16622 which describes a cell cushion having a formed setting surface, in WO 96/12426 in which the cells are produced by thermoforming and in WO 96/14004 which presents an adaptable seating surface. Graebe has originally described a square cell support in U.S. Pat. No. 5,152,023. With the same intent as JAY, previously mentioned for three of his numerous patents, GRAEBE has described cushions with interconnected cells and/or their seating surface in U.S. Pat. No. 4,953,913, in application PCT/US/9310626 published on May 26, 1994 (water filled foam base), in D342411 and D367199. In U.S. Pat. No. 4,864,671, EVANS describes cells in the shape of a Christmas tree and which can expand like an accordion having a square cross section. In WO 96/33686, BOSSHARD describes a support made of inflated cells filled with fluid, with a pressure sensing device for safety. Another cushion based on the pressure equalization principle which has been known for some time is sold under the name xe2x80x9cDOMINOxe2x80x9d by CHINESPORT of UDINE, Italy, part of their xe2x80x9cantidecubitoxe2x80x9d product line. It features cells made of four cylinders, which are half spherical at the top (bearing surface) and rigidly attached in groups of fours to create a non-expansible cell. The resulting cushion, according to the brochures, effectively combats motion sickness by restricting the lateral movements of the cells.
In the application PCT/DK93/00069 published on Sep. 2nd, 1993, RASMUSSEN describes a packaging component made out of plant fibers which seems to be economical, but cannot be reused. In WO 93/00845, COLVIN describes a dampening composite structure consisting of truncated or polygonal air cells that is reusable.
In U.S. Pat. No. 5,243,722, GUSAKOV describes an assembly of fluid filled cells which is symmetrical with respect to the median seam plane.
In FR 2599249, BEL describes air support elements consisting of small non-expansible balloons, grouped in clusters, a configuration which has for the licensed company, Coram, the disadvantage of expressly requiring a special case to maintain the clusters in place.
These various supports have the following major disadvantages: either it is impossible to expand the cells beyond their deflated volume, which required them to be staggered; or they leave voids in longitudinal and transverse arrays of non expansible cells or cells whose expansion is limited by the cell perimeter in the case of the GRAEBE supports, or even further limited at the angles if the cells have four branches ending at the four corners of a square; or a relatively complex description of poorly defined cells.
Finally, in the French application 95/08972, ROUX has described a cellular support made of interconnected cells whose major disadvantage is the total lack of information concerning the multi-ribbed cells and the small size cells, which is annoying since all the sharp angles discussed later herein have to be rounded to practical considerations. Furthermore, as it shall described later in this document, the nature of this invention allows us to describe its advantages and differences in relation to uncommonly shaped cells, left out by GRAEBE in U.S. Pat. No. 4,005,236 and U.S. Pat. No. 5,052,068.
The present invention attempts to remedy the problems associated with the previous art.
As a result, this invention pertains to mattresses, cushions, padding for medical use, reusable packaging for fragile items, dampening supports constructed with expansible cells, all featuring an upper sheet, usually formed and flexible, and interconnected expansible cells, which expand when filled with a fluid. The cross section of a cell in its natural state (deflated/empty), taken in the cell body, is delimited by at least two perimeters, an inner and an outer, which are partially virtual, concentric and located on geometric figures (envelopes) of miscellaneous shapes, i.e. square, pentagonal, octagonal, circular, irregular. The slits, cracks or crevices consisting mostly of side walls, more or less closely spaced, and parallel or not, with draft or against draft: straight, concave, convex or jagged lines connecting the outer perimeter to the inner perimeter. The use of jagged lines to connect the perimeter to the center area of the balloon or cell offers a definite advantage in that the part of the side wall of the cell which connects points located on different perimeters can actually be a straight line.